Icom IC-F3021S, IC-F3023S, IC-F3022T Transmitter Circuits, Microphone Amplifier Circuits Main Unit

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The AF signals from the analog switch (IC3, pin 11) are applied to the volume buffer amplifi er (IC6, pin 9). The buffer- amplified AF signals are adjusted its level (= audio level) by volume control pot (R315), then applied to the AF power amplifier (IC15, pin 4) and amplified to the 0.5 W of audio output power (max., at 8 Ω load).

The power-amplifi ed AF signals are output from pin 10, then applied to the internal speaker (CHASSIS; SP1) or an external speaker via [SP] jack (J2).

5-2 TRANSMITTER CIRCUITS

5-2-1 MICROPHONE AMPLIFIER CIRCUITS (MAIN UNIT)

The AF signals from the microphone (MIC signals) are fi ltered and level-adjusted at microphone amplifi er circuits.

• MIC SIGNALS

MIC signals from the microphone are applied to or bypassed the ALC (Automatic Level Control) circuit (IC24, pins 3, 5) and the A/D switch (IC25, pins 7, 1), then applied to the D/A converter (IC12, pin 1).

5-1-6 SQUELCH CIRCUITS (MAIN UNIT)

5-1-6-1 NOISE SQUELCH

The squelch mutes the AF output signals when no RF signal is received. By detecting noise components (around 30 kHz signals) in the demodulated AF signals, the squelch circuit toggles the mute switch and AF power amplifi er ON and OFF.

A portion of the demodulated AF signals from the FM IF IC (IC9, pin 9) is applied to the D/A converter (IC12, pin 24) for level (= squelch threshold) adjustment. The level-adjusted AF signals are output from pin 23 and passed through the noise filter (IC9, pins 8, 7, R42, R44–R46, C69, C70, C413). The

filtered noise signals are amplifi ed the noise components only at the noise amplifi er.

The amplifi ed noise components are converted into the pulse- type signal at the noise detector section, and output from pin 13 as the “NOIS” signal. The converted signal is applied to the CPU (IC22, pin 75). Then the “RMUTE” signal from the CPU (IC22, pin 96) to the RX mute switch (Q32) and analog switch (IC3, pins 12, 13) becomes “Low” according to the “NOIS” signal level to cut off the AF line.

At the same time, the “AFON” signal from the CPU (IC22, pin 70) to the AF amplifier controller (Q41, Q42, D21, D23) becomes “Low” and the controller turns the AF power amplifi er (IC15) OFF.

5-1-6-2 TONE SQUELCH

• CTCSS/DTCS

The tone squelch circuit detects tone signals and opens the squelch only when receiving a signal containing a matched sub audible tone. When the tone squelch is in use, and a signal with a mismatched or no sub audible tone is received, the tone squelch circuit mutes the AF signals even when the noise squelch is open.

A portion of the demodulated AF signals is passed through the active LPF (Q39) to filters CTCSS/DTCS signal. The filtered signal is applied to the CPU (IC22, pin 46). The CPU compares the applied signal and the set CTCSS/DTCS, then the CPU controls the status (“Low” or “High”) of “RMUTE” and “AFON” signals as same as “NOISE SQUELCH”.

• DTMF

DTMF signals in the demodulated AF signals are passed through the LPF (IC6, pins 5, 7) to remove unwanted components (voice signals), then applied to the CPU (IC22, pin 45) and decoded.

The level-adjusted MIC signals are output from pin 2, and passed through the MIC mute switch (Q31), HPF (IC5, pins 13, 14) and gain switch (Q34) which controls the gain of MIC amplifier (IC5) according to the Analog/Digital mode, then applied to the MIC amplifier (IC5, pin 9). The amplified MIC signals are output from pin 8, and passed through the analog switch (IC3, pins 4, 3), AF mixer (IC5, pins 6, 7) where the MIC signals and tone signals are mixed with.

• TONE SIGNALS

The CTCSS/DTCS signals are generated by the CPU (IC22) and output from pins 19–21. The output signals are passed through the 3 resistors (R222–R224) to change its waveform. The waveform changed CTCSS/DTCS signals are passed through the LPF (IC7, pins 10, 8), tone fi lter switch (Q40) and D/A converter (IC12, pins 12, 11) for level adjustment. The level adjusted CTCSS/DTCS signals are then applied to the AF mixer (IC5, pin 6).

DTMF signals are generated by the CPU (IC22) and output from pin 43. The output DTMF signals are passed through two LPFs (IC6, pins 3, 1 and pins 12, 14), then applied to the AF mixer (IC5, pin 6).

The mixed AF signals are output from pin 7 of the AF mixer (IC5) and passed through the analog switch (IC3, pins 9, 8), then applied to the AF amplifi er (IC7, pin 6). The amplifi ed AF signals are output from pin 7, and applied to the D/A converter (IC12, pin 9) to be adjusted its level (= deviation). The level- adjusted MIC signals are then applied to the modulation circuits as the modulation signals.

5-2-2 MODULATION CIRCUITS (MAIN UNIT)

The modulation circuits modulate the VCO oscillating signal using the modulation signals.

The modulation signals from the D/A converter (IC12, pin 10) are applied to the D12 at the TX VCO (Q16, D10, D13, D34) to modulate the VCO oscillating signal by changing the reactance of D12.

The modulation signals are also applied to the reference frequency oscillator (X2) via D/A converter (IC12, pins 16, 15) and the buffer (IC7, pins 12, 14), to ensure the modulation of lower frequency components of the modulation signals.

The modulated VCO output is buffer-amplified by Q15 and Q29, then applied to the transmit amplifiers as the transmit signal via TX/RX switches (D16 is ON, D17 is OFF).

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Contents VHF FM Transceivers Introduction Ordering PartsRepair Notes Table of Contents EUR Section SpecificationsSection Inside Views Main UnitPA Unit Removing the Chassis Unit Disassembly InstructionsRemoving the Main Unit Removing the PA UnitUT-108R UT-109R UT-110R Optional Unit InstallationCircuit Description Antenna Switching Circuit PA UnitReceiver Circuits RF Circuits Main UnitMicrophone Amplifier Circuits Main Unit Transmitter CircuitsSquelch Circuits Main Unit Modulation Circuits Main UnitTransmit Amplifiers PA Unit APC Circuit PA UnitOver Current Detection Circuit PA Unit PLL IC Main Unit PLL CircuitsPower Supply Circuits CPU IC22 Port AllocationsAdjustment Procedures Before Starting Software AdjustmentStarting Software Adjustment JIG Cables ConnectionPC Screen Exsample Frequency Adjustment Transmit Adjustment Convenient Receive AdjustmentMain Unit Parts ListOrder Description Location Order Description 16.3/10.3 PA UnitANT Unit PA Unit Connect UnitBC-160 Optional product Accessories Mechanical Parts and DisassemblyChassis Parts ANT UnitMP2 C, MP12 C The shape is depending on the version Diodes Semiconductor InformationMain Unit TOP View Board LayoutsANT Unit TOP View PA Unit TOP ViewConnect Unit Bottom View Main Unit Bottom ViewPA Unit Bottom View ANT Unit Bottom ViewMain Unit Block Diagram28 6# Voltage DiagramsPA Unit BC-160 SectionPage 32, Kamiminami, Hirano-ku, Osaka 547-0003, Japan

IC-F3022T, IC-F3023T, IC-F3021S, IC-F3021T, IC-F3022S specifications

The Icom IC-F3023S, IC-F3022S, IC-F3021T, IC-F3021S, and IC-F3023T are part of Icom's robust lineup of mobile radios designed for reliable communication in diverse environments. These radios are renowned for their durability, advanced features, and user-friendly operation, making them ideal for organizations in public safety, security, and industrial sectors.

One of the standout features of these models is their compact and lightweight design. These radios are engineered for easy handling and mobility, ensuring that users can carry them throughout their workday without hassle. They are designed with ruggedness in mind, meeting military specifications for durability. This makes them resistant to water and dust, allowing for reliable performance even in harsh weather conditions.

The IC-F3023S and IC-F3022S models are equipped with powerful audio output, ensuring clear sound quality, even in noisy environments. These radios incorporate advanced digital signal processing (DSP) technology, which significantly enhances voice clarity and reduces background noise, making communication crisp and efficient.

For battery efficiency, these models feature a high-capacity lithium-ion battery, which provides long-lasting power for extended operation. With features like battery saver technology, users can maximize the lifespan of their batteries, reducing downtime and operational costs.

One of the key characteristics across these models is their versatility in communication. They support multiple frequency bands and have programmable channels, allowing users to customize their communication preferences according to their operational needs. The IC-F3021T and IC-F3021S variants also support Trunked Operation which facilitates seamless communication across larger teams.

Moreover, these radios support emergency features such as an emergency button that can be programmed for instant alerts, providing an additional layer of safety for users working in high-risk environments. The inclusion of various scanning features facilitates efficient channel monitoring, ensuring that users never miss critical communications.

In summary, the Icom IC-F3023S, IC-F3022S, IC-F3021T, IC-F3021S, and IC-F3023T radios are designed to meet the demands of professional users who require high-performance communication devices. With their rugged build, exceptional audio quality, and advanced features, these radios are invaluable tools in maintaining effective communication in any operational setting. Whether for construction sites, emergency services, or security details, these models offer the reliability and function that professionals need every day.
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